Well firstly to be fair to Kallis (not a stance I'm that comfortable with

) there's absolutely no reason to believe he couldn't adapt his game to 20/20 which is not the mindless slogfest that it is often made out to be. Good orthodox slow scoring batsmen can be just as effective (something amply demonstrated by someone like Mark Ramprakash for Surrey) as the big hitters provided they properly understand their role in the side and revel in the freedom 20/20 allows them. So to drop him for a second rate batsmen like Bodi is if you are taking the tournament remotely seriously is simply not on.
Throw in the fact that the South African selectors didn't even have the balls to tell him he was dropped and came up with the "there is a lot of cricket to be played in the next 18 months and we would like to keep him as fresh as possible" line then his annoyance is understandable. Something that is completely undermined by the selection of the far more important test and one day players Ntini and Pollock who are equally deserving of the rest that has been forced upn Kallis.
However in terms of his toys out of the pram antics on being dropped (sorry rested) I agree completely with you. I know Kallis is not the sharpest tool in the shed but to get so riled up on missing this mickey mouse tournament that he would given up any chance of captaining his county and begin considering his international future in proper cricket is frankly ludicrous. If he storms off to county cricket next season in a huff I don't imagine that the South African public would be to upset.